In the production process of battery cans, battery cans produced from a steel plate by a can-making process are usually washed with tap water or industrial water to remove anything adhering to the battery can surface. The battery cans are then dried to prevent the battery can surface from rusting due to water adhering to the battery cans.
However, tap water or industrial water contains relatively large amounts of Ca or Mg. Thus, after the battery cans are washed, even if the water is removed by drying, the Ca or Mg contained in the tap water or industrial water may remain on the battery can surface, thereby causing the battery can surface to rust.
As a method for preventing battery cans from rusting, for example, Patent Document 1 proposes applying a rust inhibitor to a battery can surface to form a protective film. However, this increases the production cost. Also, the protective film may act as a resistance film which increases the contact resistance of the terminal section of the battery can.
Also, for example, Patent Document 2 proposes a method for suppressing the formation of rust due to liquid electrolyte which has adhered to a battery surface in the liquid electrolyte injection step. In this method, after a battery is produced, the battery is washed with pure water and then dried at or below room temperature in a low dew-point atmosphere.
Patent Document 1: Japanese Laid-Open Patent Publication No. Hei 09-111485
Patent Document 2: Japanese Laid-Open Patent Publication No. Hei 10-255817